Controls for transmission



April 5, 1960 R. w. WAYMAN CONTROLS ROR TRANSMISSION 5 Sheets-Sheet 1 NJONN Filed OCT.. 3, 1957 April 5, 1960 R. w. WAYMAN CONTROLS FOR TRANSMISSION 5 Sheets-Sheet 2 Filed OCT.. 3, 1957 April 5, 1960 R. w. WAYMAN 2,931,251

CONTROLS FOR TRANSMISSION Filed Oct. 3, 1957 5 Sheets-Sheet 3 2 5 REAR 32, CLUTCH Lomi- .3.3 J 65 CL TC' 5S l@ REVE/SE A //H/a/rof? jjj I 26j N//YUAL VAL VE VH L V E 2 a3 fnverzof/ April 5, 1960 R. w. WAYMAN 2,931,251

CONTROLS FOR TRANSMISSION Filed Oct. s, 1957 s Sheetsheet 4 TH/POTTLE MOD. VAL VE f@ @2&7 HAM@ April 5, 1960 R. w. WAYMAN 2,931,251

CONTROLS FOR TRANSMISSION Filed Oct. 5, 1957 5 Sheets-Sheet 5 E /26 HEAR JEfPI/a y Z /75 j? IPA/V65 CNTROL K GOM .SAFETY CNTRGLS FOR TRANSMISSION Robert W. Wayman, Muncie, Ind., assigner to Borg- Warner Corporation, Chicago, Iii., a corporation of Elinois n appuiera@ october s, i957, serial No. 637,898

'7 Claims. (Ci. 74--754) My invention relates to automatic transmissions for automotive vehicles and more particularly to hydraulic controlling mechanisms for such transmissions.

An automatic transmission may provide three different speed ratios in forward drive, that is, a low speed drive, an intermediate speed drive, and a direct drive. The direct drive may be completed by means of a fluid pressure engaged clutch, and the other two drives may be completed cy fluid pressure engaged brakes. A seiector valve under the control .of the vehicle operator is cornmonly provided for disengaging the clutch and engaging one of the brakes for the purpose of shifting the transmission from direct drive to intermediate speed drive to provide engine braking for the vehicle.

The intermediate speed brake preferably wraps or is seltener-gizing for the direction of reaction when the engine is driving, and I have found that when the transmission is downshifted from .direct drive to intermediate speed drive by disengaging the clutch and engaging thc brake rather 'high vehicle speeds, .the intermediate speed brake may slip with undue wear. This is particularly true in the case in which the transmission has been dcsigned for a vehicle engine of greater vhorsepower vthan that which is actually used and the hydraulic piston for the intermediate speed brake has Vaccordingly been reduced in size to provide a relativelysmooth engagement for shiftino to intermediate speed drive from low speed drive with the vehicle engine driving.

Transmissions of this .type ordinarily comprise a hydraulic torque converter which automatically provides a decreased torque multiplication as the vehicle speed increases, and accordingly, in order to provide smooth power train completions, the so-called line pressure which is applied to the clutches and brakes is decreased with increases in vehicle speed. Due to the slippage problem, however, mentioned above, lsuch a decrease in line pressure aggravates the slippage, and it is accordingly an object of the present invention to decrease the line pressure with increases in vvehicle speeds in only the ordinary forward driving ranges and to disable the line pressure decreasing mechanism in a so-called low range drive intended to be effective for providing engine braking.

It is a still more particular object of the invention to provide mechanism in a transmission of this type to cause the line pressure to increase, rather than to decrease, in the low range drive to assure -that no slippage of lthe intermediate speed brake can occur.

"f he transmission control system disclosed herein is an improvement on the transmission control system shown in my prior application, Serial No. 166,136, filed June 5, 195i), and in tre application of George E. Flinn, Seriai No. 5131,929, filed December 31,1956.

The invention consists of the novel constructions, arrangements and devices to oe yhereinafter described and claimed for carrying out the above stated Yobjects and such other objects as will be apparent from the :following description vof a preferred form of the invention, illus nited States Patent Q CII "ice

trated with reference to the accompanying drawings,

wherein:

Fig. l is a schematic diagram of a transmission with which the hydraulic controls of the invention may be used;

Fig. 2 is a table showing the manner in which Figs. 2A, 2B, 2C and 2D may he placed together for the pur pose of forming a schematic illustration of the hydraulic transmission control system of the invention; and

Figs. 2A, 2B, 2C and 2D are respectively parts ofthe hydraulic control system of the .invention which should be placed together in the manner indicated in Fig. 2.

Like characters of reference designate like parts in the several views.

The transmission with which my improved hydraulic controls are adapted to cooperate may be seen in Fig. i to comprise a drive shaft 25, a driven shaft 26, and interu mediate shafts 27 and 28. The shaft 25 may be the usual crank shaft of the engine 29 of the vehicle, and the shaft 26 may be connected with the usual driving road wheels 30 of the vehicle by any suitable well-known power transmitting mechanism. The shafts 27 and 23 are in effect piloted with respect to the shafts 25 and 26. The transmission comprises in general a hydraulic torque converter 31, hydraulically operated friction clutches 32 and 33, hydraulically operated friction brakes 34 and `35 and a planetary gear set 36. l

The hydraulic torque converter 31 comprises a vaned Lnpeller clement 37, a vaned rotor or driven element 35, and a vaned stator or reaction element 39. The impeller 37 is driven from the drive shaft 25, and the rotor 3d is fixed to the intermediate shaft 27. The stator 3% is rotatably disposed on a stationary sleeve 49, and a oneway brake 41 is disposed between the stator andthe sieeye 4i?. The one-way brake 41 may be of any suitablerconstruction, and, in the illustrated embodiment, comprises a plurality of tiltable sprags 42 disposed between an inner race surface 43 fixed with respect to the sleeve 4h ,and an outer race surface 44 fixed with respect to the stator 3?. The one-way brake 4i. is so arranged as totallow a free rotation of the stator 39 in the forward direction, that is, in the same direction in which the drive shaft rotates and which is indicated by the arrow 45 and prevents a rotation of the stator in the reverse direction.

The torque converter 3l functions in a manner wellknown for such torque converters for driving the rotor or driven element 3S at an increased torque with respect to the torque impressed on the impeller 37 of the converter. ri`he vanes of the stator 39 function to change the direction of tiow of duid between the rotor and irnpeller so as to provide this increased torque on the driven element 38. In this case, the reaction on the stator 39 is in the direction reverse to the direction of rotation of the dri 'e shaft 25, so that the one-way brake 41 engages and prevents rotation of the stator in this direction. When the speed of the rotor 3S reaches a predetermined value, the reaction on the stator vanes 39 changes in direction, tending to rotate the stator in the forward direction; and the brake 4i releases and allows such rotation of the stator. In this case, the torque converter 31 functions as a simple fluid coupling which drives the rotor 38 at substantially the same speed and with no increase in torque with respect to the impeller 37.

The planetary gear set 36 comprises a sun gear 45 which is xed on the shaft 28, a second sun gear 47 fixed on a sleeve portion 48 which is rotatable on the shaft 28, a ring gear 49 fixed with respect to the driven shaft 26, a plurality of planet gears 5G, a plurality of planet gears 51 and a planet gear carrier 52. Each planet gear 50 and each of the planet gears 51 is rotatably disposed on and is carried by the carrier 52. The carrier 52 is rotatably disposed with respect to the shaft 28 and the shaft portion 48 by any suitable bearings. The planet gears 51 are each in mesh with the sun gear 46 and also with a planet gear 50. The gears 50 are also in mesh with the ringV gear 449 and with the sun gear47.

The clutch 32 is arranged to connect the shaft 27 driven by the rotor 38 with the shaft 28 and the sun gear 46 fixed thereon. The clutch 32 comprises clutch discs 53 splined on a hub member 54 which is fixed on the shaft 28. The'clutch also comprises 'clutch discs 55 interleaved between the discs 53 and fixed within a Ymember, 56, that is, in turn xed to the shaft 27 so as to be driven by this shaft.

1 power for the intermediate speed power train is the same The clutch 32'comprises a movable pressure plate 57 splined within Vthe member 56 and adapted to press the friction discs 53 and 55 togetherin frictional engagement between it and an enlarged annular part 58 of the shaft 27. An annular piston 59 is provided for actuating the Y movable pressure plate 57. The pressure from the piston 59 is transmitted to the pressure plate 57 through a spring strut 60 which is in the form of an annular Belleville washer. The strut 60 at its inner periphery is acted on by the piston 59 so that its inner periphery moves axially with respect to its outer periphery and moves the pressure plate 57 which is acted on by the strut 60 at intermediate points thereof. The inherent resilient action of the strut 60 functions to return the piston 59 back into its illustrated position when uid pressure, applied as will be hereinafter described, is released from the piston.

The clutchY 33 is arranged to connect the part 56 andv thereby the shaft 27 with the shaft portion 48 and the sun gear 47 and comprises clutch discs 61 splined onto thermember 56 and clutch discs 62 splined within a member 63 which is fixed to the shaft portion 43. YA pressure plate .portion 64 is fixed. to the member 63 on one side of the clutchdiscs, and an annular hydraulic piston 65 is provided von the other side of the discs for compressing the discs between it and the pressure plate portion 64. A return spring 66 is provided for acting on the piston 65 and yieldably holding it in its clutch disapplying position.

The brake 34 comprises a brake band 67 adapted to as for the low speed powerftrain; however, for the inter-A mediate speed power train, the sun gear 47 is the reactiony element of the gear' set 36 rather than the carrier 52, the gear 47 for the intermediate speed drive being held stationary by the brake 34. Since there are sets of Vtwo planet gears 50 and 51 between the sun gear 46 and the ring gear 49; and since the sun gear 47 is in mesh with the gears 50, the ring gear 49 and thereby the shaft 26 are driven at a reduced speedy with respect to the shaft 23 which'is, however, higher than for the low speed be contracted on the part 63 for thereby braking the sun gear 47. The brake 35 comprises a brake band 68 adapted to be contracted on a drum portion 69 of the planet gear carrier 52.

In operation, the transmission has a neutral condition and provides low, intermediate and high'speed ratios in forward drive and a drive in reverse. The transmission is in neutral condition when the clutches 32 and`33 and the brakes 34 and 375 are disengaged.

The low speed forward drive maybe obtained by engaging 'the clutch 32 and the brake 35. The clutch 32 is engaged by applying fluid pressure to the piston 59. The low speed powerltrain exists from the drive shaft 25 through the torque converter 31, the intermediate shaft 27,l the clutch 32, the shaft 28 and thevplanetary gear set 36 to thershaft 26. For this drive, the reaction Von the planet gear carrier 52 or the tendency of the carrier 52 to rotate is in the reverse direction; and the brake 35 is effective to prevent such rotation of the carrier 52, so that the carrier 52 is held stationary and thus constitutes the reaction element of the gear set 36. The shaft 2S, driven as just described, drives the sun gear 46 which constitutes the driving element of the gear set 36. The drive is transmitted through the planet gears and 51 from the sun gear 46 to the ring gear 49 thus'driving the Ashaft 26 at a reduced speed with respect to the shaft 28. Torque conversion takes place in both the hydraulic torque converter 31 and also in the gear set 36, so that the torque with which the shaft 26 is driven is the product of the individual torque multiplications of Vthe hydraulic torque Vconverter 31 and the gearset 36. it will be understood, as above described, -however,'that the torque conversion produced bythe drive.

The high speed power Vtrain is obtained by allowing the clutch 32 to remain engaged and engaging the Y clutch 33 in lieu of the brake 34. Theclutch 33 may bek engaged by applying fluid pressure to its piston 65. In this drive, the shaft 27 is driven through the torque converter 31 from the drive shaft'25 as in intermediate speed drive. The shaft 27 is connected through the clutch 32 to drive the sun gear 46 as was the case in intermediatespeed drive. The clutch 33 functionsto connect part 56, which is connected to the shaft 27, with the part 63 and thereby with the sungear 47. Thus, both the sun gear 46 and also the sun gear 47 are driven by the shaft 27,'and as is well-known in connection 'with planetary gear sets', when two elements of the gear set are driven at the same speed,

'the gear set becomes locked up so that all of its gears and elements rotate as a unit. There is thus a direct drive between the shafts 27 and 26. ,The converter 31 may be expected to function as'a simplefluidcoupling, generally, in this drive; and v.there thus exists a substantially direct drivebetween the drive shaft 25 of the transmission and its driven shaft 26. v

' Reverse drive may be obtained through the transmission by engaging the brake 35 and the clutch 33. The power train for this drive is from .the drive shaft 25 through the torque converter 31,1the intermediate shaft 27, the clutch 33, the sun gear 47, the planet gears 50 and the ring gear V49 to the driven shaft 26. The brake 35 causes the planet gear carrier 52 to function as the reaction element of the gear set; and in this case, the

Yreaction on the carrier 52 is in the forward direction.

Since there are vonly the single planet gears 50 between the sun gear 47 which drives and the ring gear 49 which is driven, the ring gear 49 and the shaft 26 will be driven at a reduced speed in the reverse direction with respect to the shaft 27. For this drive, the torque converter 31 generally functions to increase torque; and thus the torque impressed on the shaft 26 is the product of the torque increased by the torque converter 31 and the planetary gear set 36.

It is believed that the construction of the transmission vwill be apparent from the diagrammatic illustration in Fig. 1 and that a person skilled in the art can supply the various detailed parts, such as bearings, to build an actual device; however, for an actual illustration of' such detailed parts, the copending application of Robert W. Wayman, Serial No. 166,136, filed June 5, 1950, which discloses a similar transmission, may be referred to.

The hydraulic control system for the transmission com prises, in general, a front pump 98, a rear pump 99, a rear servo check valve 100, a low range valve 1071, a manual valve 102, a downshift valve 103, a throttle valve 104, a compensator valve 105, a throttle modulator'valve 106,V a main oil pressure regulator valve 107, a low oil pressure regulator valve108, an orifice control valve v109, a transition valve 110, a 2-3 shift valve 111, a'rgovernor safety valve 1.1.2, a 1 2 shift Vvalve 113, a range control valve 114, a reverse inhibitor valve 115 anda governor valve 116.

The brake 34 is applied by means of a hydraulic motor 117. The motor 117 comprises a piston 118 connected by means of a bell crank 119 and a strut 120 with one end of the brake band 67, the other end of the brake band 67 being held iixed by means of a strut 121. The motor 117 has a brake applying uid pressure cavity 122 and a brake disapplying fluid pressure cavity 123, and a spring 124 acts on the piston tending to hold it in its brake disapplying position. Fluid pressure supplied to the cavity 122 moves the piston 118 against the spring 124 so as to move one end of the brake band 67 to engage it with the drum 63. 1t may be noted at this point that the direction of reaction on the sun gear 47 and the drum 63 is in the reverse direction as indicated by the arrow A when the brake 34 is engaged for the intermediate speed ratio power train. This direction is opposite the direction of rotation of the drive shaft indicated by the arrow and the drum 63, in tending to rotate in this direction, augments the action of the .strut 120 in engaging the band 67 and causes increased band engagement, since the drum 63 tends to carry the end of the band acted on by the strut 120 in the same direction in which this end of the band is urged by the strut 120. It is apparent that the band 67 wraps or is partially self-energizing for this rotative tendency of the drum 63.

The brake 35 is engaged by means of a fluid pressure motor 125 which comprises a piston 126 movable by fluid pressure applied thereto against the action of a spring 127. Motion of the piston 126 is transmitted to one end of the brake band 68 by means of a bell crank 128 and a strut 129, the other end of the brake band 68 being held xed by means of a strut 130. In low speed drive through the transmission, the reaction on the planet gear carrier 52 and on the drum 69 is in the reverse direction as indicated by the arrow B, and this reaction or tendency to rotate tends to unwarp the band 68 with respect to the drum 69. For reverse drive through the transmission, the reaction ou the brake drum 69 is in the forward direction as indicated by the arrow C, that is, in the same direction as the drive shaft 25 rotates. The tendency of the drum 69 to rotate in this direction assists the strut 129 in forcing the movable end .of the band 68 to move in the direction indicated by the arrow C, l

and the brake 35 thus wraps or is self-energizing for this direction of reaction, so that the braking effect is greater than would be the case if there were no tendency for the drum to rotate. The reaction on the drum 69 is greater for reverse drive than for low forward drive, and hence, the brake 35 has been constructed to wrap for the reaction for reverse drive instead of that or low speed forward drive.

The pump 98 may be of any suitable xed displacement type and may comprise an outer gear 131 and an inner gear 132 and a crescent-shaped casing portion 133 between the gears. The gears 131 and 132 carry Huid between their teeth and across the inner and outer surfaces of the casing portion 133 so as to draw fluid from an inlet conduit 134 and discharge it into an outlet conduit 135. The inlet conduit 134 is adapted to draw uid, such as oil, from a sump 136. The pump 9S is driven directly from the drive shaft 27 through the impeller 37. The pump 99 is of the same construction as the pump 98, having inner and outer gears 137 and 138, and is driven from the driven shaft 26 of the transmission. The pump 99 draws fluid from the sump 136 through an inlet conduit 139 and discharges it into an outlet conduit 140.

A conduit 141 constitutes the supply or line pressure conduit for engaging the power train completing friction clutches and brakes and also for supplying various valves in the transmission control system with uid pressure. A check valve 142 is disposed between the conduits and 141 ,and comprises a piston 143 yieldably held in its closed position by means of a spring 144. The check valve 142 blocks lluid liow from the conduit 141 to the conduit 140 and the rear pump 99.

A similar check valve 145 comprising a piston 146 and a spring 147 acting on the piston is provided between the line pressure conduit 141 and the outlet conduit 135 for the front pump 98. The check valve 145 functions to prevent uid tiow from the line pressure 1, conduit 141 to the conduit 135 when the pressure in the latter conduit is lower than in the conduit 141.

The main pressure regulator valve 107 functions to regulate pressure in the line pressure conduit 141. The valve 107 comprises a piston 148 having lands 149, 150, 151 and 152. A spring 153 is provided for moving the piston 148 downwardly as seen in the figure. The valve 157 comprises ports 154, 155, 156, 157, 158 and 159. rhe ports 156 and 157 are connected with the line pressure conduit 141, and the port 154 is connected with the outlet conduit 135 of the pump 98. The ports 155 and 159 are permanently connected around the piston 148.

The valve 108 is a regulator valve for regulating the pressure within the hydraulic torque converter 31. The valve 108 `comprises a valve piston 160 having lands 161, 162 and 163. A spring 164 is provided between the land 161 and a stationary part for yieldably holding the piston downwardly. The valve 108 comprises ports 165, 166, 167, 168, 169 and 170. The port 165 is connected with the portsv159 and 155 which are in per manent connection around the valve piston 148 and also with the torque converter 31 through a torque converter .inlet conduit 171; the port 166 is connected with the port 158 of the valve 107; the port 167 is a bleed port adapted to discharge into the sump 136; the port 168 is connected by means of a torque converter outlet conduit 172 with the torque converter 31; the port 169 is connected with a conduit 173 which supplies lubricatingoil to any suitable parts of the transmission; and the port is connected by means of av conduit 174 with the pump inlet conduit 134.

The governor valve 116 is for the purpose of providing a speed responsive fluid pressure for causing various ratio changes through the transmission. The governor valve 116 comprises a casing 175 which is xed on the driven shaft 26 and a piston 176 slidably disposed in a cavity within the casing 175. The piston 176 is provided with lands 177 and 178. The governor valve 116 comprises ports 179, 180, 181 and 182. The ports 181 and 182 are bleed ports discharging into the sump 136. A governor weight 183 extends through and is slidably disposed within the governor piston 176. The weight 183 has a spring retainer washer 184, lixed on its inner end and a spring 185 extends between the retainer washer 184 and an internal shoulder formed within the piston 176 for yieldably holding the Weight 183 and the valve piston 176 together in the relative positions in which they are illustrated.

The throttle valve 104, the compensator valve 105 and the throttle modulator valve 106 provide pressure that varies with the position of the accelerator of the vehicle for varying the shift points of the transmission and also varying the pressures that are applied to the various clutches and the brakes of the transmission. The throttle valve 104 is under the control of the downshift valve 103. The downshift valve 103 comprises a valve piston 186 having lands 187 and 188. The downshift valve 103 comprises ports 189, 190 and 191. The port 190 is connected with the line pressure supply conduit 141. The valve piston 186 is under the control of the vehicle accelerator 192 by any suitable connecting mechanism so that when the accelerator 192 is moved toward an open throttle position, it coordinately moves the piston 186 to the right as seen in the drawings. It will be understood that the accelerator 192 has the usual connections f with the carburetor of the vehicle engine 29.

The Athrottle valve V104 comprises a piston 19.3`hav-ing lands 194, 195 and ,196. y VThe valve 104 comprises ports 197, 198, 199 andpZGl. VA spring 2011s provided between the valves 103 and 104. The port 197 is connected with the line pressure supply conduit 141; the port 198 which is relatively restricted is connected with the port 199; and the port 2i0'isa bleed port. A bleed port 202 is provided between the two valves 103 and 104.

The Vthrottle modulator valve 106 Vcomprises a piston 203 having lands 204 andr205. A sheet metal spring retainer .206 embraces anY end of the'piston 203 and a spring 207 is provided between the land 204 and the retainer 206. vA. spring 298 is provided between the land 205 and the adjacent end of the cavityin which the piston 203 is disposed. The valve 1516 comprises ports 209, 210, 211, 212, 213 and 214. Theports 209 and'211are bleed ports, and the port 210 yis connected with a throttle pressure supply circuit 2 15 to which the ports 198 and'199 of the throttle valve 104 are Valso connected.

The compensator valve 105 comprises pistons 216, 217, and 218. The piston 216 constitutes a simple plug slidably disposed'in a stationary sleeve 219. `The piston 217 comprises lands 220, 221, 222, and 223. The piston 218 comprises lands 224 and 225. A spring 226 is disposed between the land 220 and the fixedrsleeve 219and a spring 2,27 is disposed between the land 220 and the movable plug 216. l The compensator valve 105 is provided with ports 228, 229, 2311231, 232,233, 234, 23s, 23e and231. The port v229, which is relatively restricted, and the port 228 are connected by means of a compensator pressure supply conduit 238 with the ports158, and 166 of the Vpressure regulator valves 107 and 108; the port 230 is connected vby means .of a` conduit -239 with the port 213 of theV valve 106; the port 231 is connected by meansof a conduit 240 Vwith the port 2172 of the valve 106; the port 232 is connected with a governor pressure supply conduit 241 that is also connected with Vthe port 1,80 of the governor valve 116, the ports 233 and 234 are connected with theline pressure supply conduit 141; the ports 235 and 236 are bleedports; and the port 237 is also connected with the governor pressure supply conduit 241 through the low range valve 101`as will be hereinafter describedv in greater Y detail.V

The various ranges of operation ofthe transmission are under the control of the manual valve 102. The valve 102 comprises the valve piston 242 having lands 243, 244 and .245.: 'lhevalve is provided with ports 246, 247, 248, 249,v 250, 251,252 and 253. TheA port 24S is connected by means of a conduit 254with the piston 118,

.particularly withthefcavity 122; the Vports 249 and 250 are connected withY the line pressure supply conduit 141; and the port 251 is connected by means of a conduit 255 withV the port 191 ofthe downshift valve 103. The manual valveV pston 242 is controlled from the drivers compartment by means of a selector lever256 located directlybeneath the vehicle steering wheel 257, the selector lever being connected by any suitable connecting mechanism with the piston 242, so that the piston 242 can be moved into any of its principal positions which are N, D-2, D-l, L, and R corresponding to neutral,` high drive range with the start in intermediate, high drive range with Vthe start inrlowlow range andsreverse drive, respectively.

The'2-3 shift valve 111 causes engagement and disenin the drawing, and a spring 266 is provided between the land 261 and thepiston 258. The piston 260 is also a simple plug.l` The valve 1 11 is provided withV ports 267, 268, 269, 270,271, 272,V 273, 274, 275, 276,Y 277,

"means of a conduit 328 with the conduitv 281 27s 1113.272. The ports zsrird 26s areconngcred to; gether; the ports 269 and 271 are connected by means of a branch conduit 280-withthe governor pressure conduit 241; the port 270 is a bleed port; the ports 273.and '277 are connected by means of a'conduit 281 'with the piston65 for the rear clutch 33; Vthe port 274 is connected by means of a conduit 282 with the port 246 of the manual valve 102; the port 278 is connected by means of Vaconduit Y283 with the lport'1789 of the downshift valve 103; andthe port 279 is connected with the conduit 215 that is'connected to the port 199 and 1,98 vof the throttle va1ve104. A The l-2 shift valve `113V causes engagement and disengagement'of the brakes `S34-and 35 for causing changes betweenthe lirst andthe second speed'drives. VThe valve 113 comprises -a valve piston 284 provided with lands '285, 286,287,288, 239 and 290.. The .1-2 shift .valve '-113comprises ports291, 292, 293,'. 294,.y 295, 296; 297., 298, 299,Y 300 and 301. The port 292 is connected by -means-of a conduit 302 with the port 251 of the manual valve'102; the ports 293 and 296 are bleed ports; the port 294 is connected to the VVVconduit 254 and thereby with the supply cavity 122 of the servo motor for the brake 34; the port 297 is connected to the conduit 283; the port 298v is connected by means of a conduit 303 with the ports 267 and 268 of the 2-3 shift valve 111; the port299 is connected with the port 301; and A-the port300 is ableed port. A spring 394 is provided in the valve 113 Afor Vurgingthe piston 284 upwardly. 30

TheV range control Vvalve '114 1s Yunder lthe control of the lma'nu'al valver102'arnd determine's'the starting speed ratio forVV drive range operation.`y The lrange control valve 114'c`orn'prises a valve piston305-having a land 306. The

valve 114 comprises ports 307, 308, 309, and 318.',The

port 307 is connected to the' conduit'241; the ports 388 and 389 are connected by means of a'conduit 311 with v the port 291v of the 1 2 shift valve 113; and the Yport 310 is connected by means of a/ conduit 312 with the port 253 lof the manual valve 102. v

The transition valve 110 is Vfor the purpose of preventing applicationV ofV the rear brake'35 in the two drive ranges and comprises v'alve pistons V313 and 314. vThe piston' 313 is a simple plug; and the piston 314 is pro- -vided with lands 315, 316 and 317. A spring 318 is provided on one end of the piston 314 for moving the piston downwardly. The 'valve 110 comprises ports^319, 328, 321, 322,' 323, 324 and 325; The port 319 is connected by means of a conduit 326 with the;disapply cavity 123 of theservo Ymotor 117 for the front brake 34; the ports 321 and 322 are bleed ports; the Vport 323 is connected by means of a conduit 327 with the servo motor 125 for the brake 35 and the port 325 is connected by and thereby withthe clutch 33.

Theoriiice control valve 109 is for the purpose of at times restricting flow of uid with respect to the servo motors of the various friction engaging devices of the transmission and comprises valve pistons 329 and 338. The piston 329 is a simple plug, and the piston 338 comprises lands331, 332, 333, and 334.` A spring 335 is vdisposed at the lower end of the piston 330 for yieldably holding it in its illustrated'position.` The valve 109 comprises ports 336,337, 338, 339, 341i, 341, 342, and 343. The port 336 is connected to the conduit 327 through aY restriction 344; the port 337 is connected'to theconduit 215; the port 338 is connected by means of a conduit 345 to the port 276 of the 2-3 shift valve 111; the port339 is connected through a restriction 346 with the conduit 345; the port 340 is permanently connected around the piston 33@ with the portV 339 and is.con nected to the conduit 326; the port 341 is connected by means of a conduit 347 with the port 275 of the 2-3 shift valve 111; the port 342 is connected by means of a Sausage-s1 `duit'349with'thepo'rt321') 'of the'trans'ition'valve 4110 and by means of a conduit 350 with the port 272 ofthe 2-3 shift valve 111.

The reverse inhibitor valve 115 is for the purpose of preventing a completion of reverse drive when the selector 256 is moved into its reverse drive position at relatively high forward vehicle speeds. The reverse inhibitor valve comprises a piston 351 having lands 352, 353 and 354. A spring 355 is provided for yieldably holding the piston 351 downwardly lin its illustrated position. The valve 115 comprises ports 356, 357, 358, 355, 360, 351 and 362. The port 356 is a bleed port; the port 357 is connected by means of a conduit 363 with the conduit 350; the port 35S is connected by means of a conduit 364 with the port 252 of the manual valve 162; the port 359 is connected to the conduit 2541; the port 360 is connected by means of la conduit 365 with both the piston 59 vfor the front clutch 32 andalso with the port 179 of the governor :116; the port 361 istconnected by means of a conduit 365 with the port 247 .of the manual valve 162; and the port :362 is connected with the conduit 241.

The governor safety valve 112 is for the purpose of assuring that no governor pressure existsfor reverse driving. The governor safety valve 112 comprises a piston 367 having lands 368 and 369. A spring 3743 is provided for yieldably holding the piston 367 downwardly in its illustrated position. The valve v112 comprises ports 371, 372, 373 and 374.Y The ,port 371 and the 4port 372 are connected together and to the conduit 251; the port 373 -is a bleed port; and the yport 37A. is connected by means of ra branch conduit l375 with the conduits V31%? and 359.

The rear servo check valve i) is for the purpose or checking fluid ow at times with respect to the rear servo motor 125. The valve 16) comprises a piston 376 having two lands 377 and 373. A spring 379-is disposed lbetween the piston 376 and one end of the cavity for the piston 376, as shown. The valve vlll() isprovided with ports 386, 381, 332 and 383. The port 3853 is connected by means of Va conduit 384 with the port 324 of the transition valve 119; the port 381 is permanently connected with the port 331i around the piston 376 and is connected through a restriction 385 -with the conduit 336 that is connected to the-conduit 347; the port 332 is connected to the conduit 336; .and the port 383 is connected to the conduit 215.

The low range valve 101 is Vfor -the 'purpose of changing at times the regulation of the compensator valve 1155. The low range valve 191 comprises a piston .337:having lands 338 and 389. -T he valve 101 is provided with-ports 4399, 391 392 and 393. Theport '390 is connected yby means of a conduit 39d with theport :214 of the throttle modulator valve 106 and by means of a conduit 395 with the conduit 255; the port 391 isa bleed port; the port 392 is connected with theport 237 of the compensator valve 105; and the port v393 'is connected with the conduit 241.

in operation, the transmission is maintained in its various ranges under the control of the manual valve 192. The transmission is in neutral condition when the manual selector valve piston 242 is-in its N'or neutral position. When the -engine 23 begins operating, thepu'mp 9S driven by the engine supplies line pressure `to the conduits 135 and 141 and connected conduits, pumping oil from the sump 136 through the pump inlet 135. The conduit 1411 is connected with the conduit 135 through the check valve 145, the check valve '145 being eld open by the uid pressure from the pumpA 98. This uid pressure in the conduit 141 holds the check valve 142 closed so that fluid cannot escape through the rear pump 99, which is assumed inoperative at this time with the vehicle being stationary. In the'neutral condition of the piston 242, the groove between the lands 244 and 245 connects the-ports 249land250 supplied'withline '1D "pressure `through the conduit 1111, and Ythe lands block ow of line pressure to any of the other ports of the manual valve 102. The manual valve piston 242 thus prevents application of uid pressure to the engaging pistons Jfor any of the power train completing clutches and brakes of the transmission.

The main oil pressure regulator valve v167 functions for all conditions of the transmission and its hydraulic control system to regulate the line pressure in the conduit 1411 and 'connected conduits'to predetermined maXimum values, For this purpose, the line pressure from the `conduit is supplied through the port 157 between the lands 151 and 152; and, since the land 151 is of Alarger diameter than the land 152, the line -pressure applied to these lands tends to move the regulator Vvetve piston 1:13 upwardly against the action 'of the .strength that theport 154 will not be thus opened by .line pressure influence on the valve piston l14S until a `certain Xe'd value of line pressure is reached.

r'his fixed 'value of line pressure is maintained by the valve 1117 4in thus Jmetering and relieving excess duid under pressure from the conduit 141, assuming that there are Vno other influences on the piston 148 than just mentioned.

For most conditions tof operation, however, an'addi tional variable `force is applied tothe piston 'tending to move it, and this third force is due to uidpressure of different values (which may be termed compensator pressure) lapplied to the Alower end of the piston 14.8 throughthe port 153 and conduit 233. For the neutral condition ofthe transmission, whenthe accelerator `192 is in its closed throttle, relaxed position; the compensator lpressure `is equal to'full line jpressure which is supplied to the lower end of the piston 14S through the port 153. Line pressure flows from the conduit 141 through the port 234 of the compensator valve 165, the groove between the'lands 22@ and 221, the `port 223 and the conduit 233m the port 153. vLine pressure kissupplied from the compensator pressure conduit 233 through the port 229 between the lands 221 and 222; and, ysince the land 221 is larger than the land 222, this line pressure tends to vmove the compensator valve pistou 217 to the yleft against the actions of the springs 227 and 226. kHowever, for this condition of operation, the springs acting on the Apiston Y217 are of ysurlicient .strength to hold the piston 217 to the'limit of its movement to the right.

The "fluid pressure applied to the main oil regulator valve 'piston'143 on itslower endprovides a force acting "against the "spring 153 tending to move V.the piston 1423 Vupwardly `as seen in the gure to more tfully open the Aport 154 to the conduit 171. The full line pressure applied to the lower end of the piston 14S thus maintains the line pressure in the conduit 141'and connected conduits at a predetermined minimum which, for one certain embodiment of the invention, is v75 p.s.i.

MT he secondarymain regulator valve 108 regulates the uid pressure'within the conduit 171 and thereby within the torque converter 3110 which the conduit '171 supplies luid pressure. The pressure in the ports 155 and 159 'and in the conduit 171 is applied between the lands 161"and -162V of the low oil pressure regulator valve piston 16@ through the port 165. Since the land 161 is larger than the land 162, this huid pressure tends to move thepiston 'upwardly against the action of the spring 164i.l to open up the port 169 and meter fluid oetween the land 161 and an edge of the port 169. Thus, as theruid pressure inthe conduit 171and in the converter 31 tends vto increase, the excessive duid pressure is -dischargedtthrough the port 169;,andtheepressure in .the conduit 171 and converter 31 is regulated to a predetermined maximum.

The conduit 173 is connected to various working parts of theV transmission for lubricating them; and, when this conduit is filled, the valve piston 169 moves slightly farther against the action of the spring 164 on a slight increase in pressure in the converter 31 so as to relieve uid from the port 168 through' the groove between the lands 162 and 163 and through the bleed port 167.

. At this time, the regulating effect ofthe valve 198 takes place'between `the land 162 and the lower edge'o the port 168, and the uid flows through the conduit 171 vand through the torque converter 31 to the conduit 172 which is the uid discharge conduit for the torque converter 31.

LThe compensator pressure in the conduit 238 is also applied to the valve piston 168 `for changing the regulated converter pressure in the conduits 171 and 172 and in the torque converter 31 for various conditions o'f operation of the transmission and controls. The pressure on the lower end or" the valve piston 164B tends to move the piston 163 upwardly against the action of the spring 164 to open the discharge port 163 for the torque converter to the oleed port 167 and to thus further relieve and decrease the pressure Yin the conduits 171 and 172 and converter' 31. With full line pressure in the conduit 238 for conditions or" operation just mentioned,vthe regulated converter pressure in the torque converter 31 is at a minimum which, for one particular embodiment of the invention, is substantially p.s.i. K Y

Under certain relatively abnormal conditions, as, for example, when the oil in the'sump 136 is cold; the conduitr174 relieves the fluid pressure in the converter 31 and in its supply conduit 171. The resultant increased pressure due to cold oil in the conduit 171 applied to the relatively large land 161 will move the piston 169 stillV farther upwardly against the action of the spring 164 so as to connect the ports 178 and 165 by means of the groove between the lands 161 and 162. In this case, the regulating action by the valve piston 161i is by virtue of a metering effect betweenY the lower edge'of the land 161 and the port 17?, and the excessive uid owing through the port 1741 hows directly through the conduit 174 to th inlet conduit 134 of the pump 98.V K

vi'he transmission and its control system are co'nditioned for operation in the D2 range, that is, in automatic Y range in which theV vehicle starts in intermediate speed drive, by moving the manual selector valve piston 242 'into its D2 position. in this position, the piston 242 provides a connection between the ports 253, 246, 247, 243 and 249 by means of the groove between the lands 243 `and 244. rille port 249 carries line pressure, being connected with the line pressure supply conduit 141. rt'he line pressureis thus supplied to the ports 248, 247,. 246 and 253. Y

Pressure from the port 248 flows through the conduit 254to the port 359 of the reverse inhibitor valve 115 and is blocked at that po'rt by the land 353 of the inhibitor valve piston .351 at this time. Line pressure is also supplied from the conduit 254 to the apply cavity 122 of the servo motor 117 for the front brake 34, and the piston .118 thus moves and applies the band 67 of the brake 34 t engage the brake through the intermediary of the bell crank 119. Line pressure is also' supplied from the conduit 254 to the port 294 of the l-2 shift valve 113 but is blocked at that port at this time as will be described.

The line pressure in the port 247 flows through the conduit 366, the port 361 of the Vreverse inhibitor valve Y 192 owsthrou'gh the conduit 282 to the port 274 of the 2-3 shift valve 111, and the Vland 263 of this valve blocks the port 274 at thistime.

The line pressure at the port 253 of the manual valve 192 ows through the conduit 312 and the port 310 of the range controhvalve `below the piston V3415 of this valve, and through` the .port 39and the conduit 311 to the po'rt 291 of the l-2 shift valve 113. The line pressure below the valve piston 305 at this time maintains' the piston '305 in its illustrated position. The line pressure applied through the port 291 acts on the land 290 of the l-Z shift valve and moves the piston 284 of this valve to its intermediate speed position at the limit of its movement downwardly as seen in the gure against the action o'f the spring 394, so that the land 28S ,of the piston 284 blocks the port 294 which is supplied with line pressure at this time as has been described.V

Since the clutch 32 is engaged due to line pressure from the port 247 of the manual valve and the brake 34 is engaged due to line pressureY from the port 248 of the manual valve, the transmission is in'intermediate speed drive. Y

When the intermediate speed power train is completed as just described, by engagement of the clutch 32 and the brake 34, the accelerator 192 is assumed to be in its closed throttle position with the vehicle engine crankshaft rotating at idling speed. Under these conditions, insuticient power is transmitted through the intermediate speed power train and in particular through the hydraulic torque converter 31 for driving the driven shaft 26 and the vehicle, and the drive may be made effective for driv ing the vehicle by simply depressing the accelerator 192 to open the engine throttle.

Throttle opening movement of the accelerator 192 also has other effects on the hydraulic control system, including an increasing of the line pressure in the conduit 141 and connected conduits for increasing the applying pressure for the brake 34 antil the clutch 32, and throttle opening movement also effectsan increasing of the uid pressure within the hydraulic torque converter 31.

The accelerator 192 acts on the throttle valve piston 193 through the intermediary of the downshift valve piston 186 to provide a throttle pressure in the conduit 215 which is less than the line pressure in the conduit 141 and which increases from zero at closed throttle position of the accelerator to Aline pressure atV open throttle position. The throttle valve`104, like the valves 107 and 108, is ya regulator valve providing a variable fluid pressure by metering uid ow between a valve land and a valve port in accordance with variable forces impressed on the valve. The accelerator 192 tends tomove the throttle valve piston 193 toV the'right 'as' seen in the figure, upon depression of the accelerator, by Vmeans of the downshift valve piston 186 and Vthe spring 201. Such movement of the throttle valve piston 193 provides a connection between the ports 197'and 199 through the groove between the lands 194 and 195,admitting uid under pressure into the conduit 215 through the port 199. The

- pressure in the conduit 215 flows back through the port 198 and isthus eiective on the lands 195 and 196; Since the land 195 is of larger diameter than the land 196, the uid pressure on the lands tends to move the valve pistou 193 back to the left against the action of the spring 201, so that the land 195 tends to again close the port 197 and block further admittance of fluid pressure to the conduit 215. The greater the depression of the accelerator, the greater will be the force from the spring 261 on the throttle valve piston 193, and the greater must be the pressure in the conduit 215 for closing the port 197 by the land 195; and hence, the valve 104 has a regulating action to provide a throttle pressure in the conduit 215 which increases with accelerator depression.V

The throttle pressure from the throttle 'valve 104 is supplied through the conduit 215 to the throttle modulator valve 106 through the port 210. The valve 106 functions to provide a limited or so-called modulator pressure in the conduit 239. This limited Vpressure in the conduit 239 is the same as the throttle'pressure in the conduit 215 up to a predetermined maximum value, and for further increases in throttle presure corresponding to increased openings of the engine throttle, the modulator pressure in the conduit 239 remains at this predetermined maximum value. The throttle pressure in the conduit 215 ows through the port 210 of the throttle modulator valve and through the groove between the lands Zeri and 205 to the port 213 and the conduit 239. The spring 203 is a relatively light spring as compared to the spring 207, and this spring 208 functions to normally maintain the valve piston 203 in its illustrated position with the spring retainer 205 contacting the adjacent end of the bore for the piston 203 and with the spring 207 holdin7 the retainer 206 and the piston 203 at the limit of their movement apart. The spring 208, under these conditions, is substantially at its free length and assures that the ports 210 and 213 remain in communication by means of the groove between the lands 204 and 205 until the modulator pressure in the conduit 239 reaches its predetermined value.

The modulator pressure in the conduit 239 is applied to the lands 2de and 205 of the throttle modulator valve 106, and since the land 204 is larger than the land 205, this fluid pressure tends to move the piston 203 to the left against the action of the spring 207, the spring retainer being bottomed under these conditions on the adjacent end or the cavity in which the piston 203 is d isposed. When the fluid pressure in the conduit 239 reaches its predetermined maximum value, the pressure moves the piston 203 to the left and closes the port 210 by means of the land 205, so that the pressure of the fluid in the conduit 239 increases no further. In the particular embodiment of the invention mentioned before, the modulator pressure in the conduit 239 had a maximum of 22 p.s.i. at about 25% throttle opening, and the modulator pressure remained constant for additional throttle opening movements of the accelerator.

The modulator pressure in the conduit 239 is applied to the compensator valve 105, which is a regulator valve, for providing a compensator pressure in the conduit 238 that decreases with depression of the accelerator pedal for initial throttle opening movements of the accelerator. The compensator pressure in the conduit 238 also increases with the speed of the driven shaft 25 and the vehicle. ln this connection, the action of the governor valve 116 in producing a governor pressure in the conduit 241 which is connected to the compensator valve, will now be described.

The governor valve 116, like the valves 104 and 105, is a regulator valve; that is, it produces an output pressure that varies gradually with changing forces on the valve. The casing 175 for the valve 116 rotates with the driven shaft 2e of the transmission, and the valve piston 176 and the weight 183 tend to move outwardly under the influence of centrifugal force. The weight 183, in particular, has a relatively large centrifugal force acting on it, and this force is transmitted to the hollow valve piston 175 by means of the spring 185 disposed between the piston 17-5 and the spring retainer 184. Line pressure is present in the conduit 355; and, on outward movement of the valve piston 176, iiuid ows through the port 179, the groove between the lands 177 and 178, and the port 130 into the conduit 241 to supply pressure to the latter conduit. The pressure in the conduit 241 is applied to the facing ends of the lands 177 and 178, and since the land 177 is larger in diameter than the land 17S, this tluid pressure tends to move the piston 176 inwardly of the valve casing 175, so that the land 177 will move over the port 179 and block any further admission of Huid pressure to the conduit 241. A balance is attained between the centrifugal force effective on the valve piston 176 tending to move the piston outwardly of the casing 175, which increases with vehicle speed, and the force in the conduit e'lective on 'the lands 177 and 178 tending to move the piston 176 inwardly, which increases with the pressure in the conduit 241, for every speed of the driven shaft 2o. The vaive piston 176 thus meters the tlow of huid under pressure to the governor output conduit 2i1 between the land 177 and the inner edge of the port 179 and provides a regulated governor pressure in the conduit 241 that increases with the speed of the driven shaft 26 and of the vehicle. r1`he function of the spring 185 effectively between the weight 183 and the valve piston 176 is to allow the weight 183 to move outwardly of the -casing 17S and radially with respect to the shaft 2e without corresponding movement of the piston 17e 'at the higher speeds of the shaft 25. This arrangement provides a governor pressure that increases more gradually with increases in speed of the driven shaft 26 than would be obtained if the piston 176 has a solid connection with the weight 133.

The governor pressure in the conduit 241 that increases with the speed of the driven shaft 26 and of the vehicle is impressed through the ports ..32 and 237 on the compensator Valve and particularly on its pistons 216 and 223. The governor pressure applied on the piston 218 through ti e port 232 is not immediately effective on the piston 217, which is the regulating piston of the compensator valve 105, when the vehicle is being started, since line pressure is supplied between the lands 224 and 225 from the conduit 14,1 and the port 233. The governor pressure starts from zero when the vehicle is at a standstill and increases, while the line pressure is at some much higher value, such as 75 p.s.i. under the same conditions. Since the land 225 is larger than the land 224, the piston 21S is held to the limit of its movement to the right out of Contact with the regulating piston 217 until the governor pressure increases sufficiently to overcome the er`r`ect or" line pressure on the lands 224 and 225. 'Ehe governor pressure in the conduit 241 is initially, at low speedsof the vehicle, effective through the valve piston 216 on the regulating valve piston 217. The governor pressure is applied through the port 237 on the piston 21d and force on the piston 216 is transmitted through the spring 227 to the piston 217 tending to move the latter to the right, the force so impressed on the piston 217 increasing with governor pressure and vehicle speed. At this time the ow range Valve piston 337 is in its illustrated position.

The modulator pressure in the conduit 239 that increases with accelerator opening to a predetermined maximum is impressed on the lands 222 and 223; and since the land 222 is larger than the land 223, this modulator fluid pressure tends to move the compensator piston 21'?J to the left. This is just opposite to the etect of the increasing governor prcssure in the conduit 241.

Line pressure is supplied to the port 234 from the conduit 141, and the piston 217 functions to regulate so as to provide compensator pressure in the conduit 238. This compensator pressure increases with increasing governor pressure in the conduit 241 and decreases with increasing throttle pressure in the conduit 215 and modulator pressure in the conduit 239. 227 tend to hold the piston 217 to the limit of its movement to the right opening the port 23d by means of the groove between the lands 220 and 221 to the port 228 and the compensator conduit 23d. Fluid thus fiows into the compensator conduit 238. The compensator pressure in the conduit 238 flows through the port 22E between the lands 221 and 222 and tends to move the piston 217 to the left so as to close the port 234 by means of the land 221, this return movement of the piston 217 being by virtue of the fact that the land 221 is larger than the The springs 226 and vehicle speed.

land 222. Thus, the land 221 meters uid flow betweenit and an edge of the port 234, providing a certain regulated compensator pressure in the conduit 238. The governor pressure tends to move the piston 217 to the right as above described so as to move the land 221 off the port`234 and admit further uid pressure to the compensator conduit 238. Thus, the compensator pressure Yin the conduit 238 increases with governor pressure and The modulator pressure, as above described, tends to move the piston 217 to the left to close the line pressure supply port 234 by means of the land 221, and thus, theY compensator pressure in the conduit 238 decreases with increasing throttle pressure and modnlator pressure.

The piston 21S, at higher speeds of the vehicle, reduces the effect of the governor pressure just described in increasing the compensator pressure in the conduit 238. As the governor pressure in the conduit 241 rises, eventually it is sufficient so as to move the piston 218 to the left. so that'this piston acts on the piston 217 and tends to move the latter piston to the left against the force due to the governor pressure transmitted through the pistonV 216. The piston 218 is moved to the left by the governor pressure when the governor pressure overcomes the effect of the line pressure impressed through the port 233 on the lands 224 and 225 tending tomove the piston 218 to t e right. The line pressure in the conduit141 and Vapplied to the lands 224 and 225 decreases with increasing governor speeds as will be hereinafter described, and

y there thus exists a crossing of the eifect of line pressu.e

which decreases with increasing vehicle speed and governor pressure which increases with vehicle speed, both effective on the piston 218, after which the piston 218 is effective on the valve piston 217'and its regulating action.

When the vehicle begins to move, after the accelerator 192 has been moved toward its open throttle position to increase the speed and power output of the vehicle engine, the rear pump 99 begins its pumping action and draws fluid through the intake conduit 139 from the sump 136 and discharges it into the outlet conduit 141). Thecheck valve 142 remains closed Vuntil the pressure of the iluid dischargedY by the rear pump 99 increases toa suicient value to overcome the forces due t the line pressure and the spring 144 on the piston 143; and at this time, the

the line pressure conduit 141 then reverses and closesy the check valve 145 by moving the piston 146 upwardly onto its seat. r111e closing of the check valve 145 blocks discharge by the front pump 98 into the line pressure conduit 141 and its connected conduits, and the rear pump now becomes the sole supply of line pressure for the conduit 141 and connected conduits. The line pressure in the conduit 141 is impressed on the main oilpressure regulator valve piston 14S and particularly its lands 151 and 152 through the port 157 to provide the regulating action between the land 149 and the port 154 when the front pump alone is providing the line pressure, and when the line pressure increases slightly due to closing of the check valve 145 and opening of the check valve 142 as just described, the piston 148 is moved upwardly slightly, since the line pressure is effective to move the piston 148m this direction due to the land 151 being larger than the Vland V152. Under these conditions, Vthe port 154 is fully opened Vso as to connect the ports 154 andl 15?. The regulating eEect of the valve 107 is now between the lower edge or" the land 159 and therlower edges of the ports 155 and 159, with the excess pressure produced by the rear pump 95 escaping from the port 156 and the groove between the lands 150 and 151 to the ports 155 and 159. With the rear pump 99 being thus active to produce the line pressure, the line pressure is now regulated exactly as has been previously described, except that it is slightly higher in value and is metered between the land 15d and-ports 155 and 159 instead-of 16 betweenanedge of the port 154 and the land 149.V The front pump now functions Ysolely to supply uid under pressure to the converter 31 and for lubrication.

ThecompensatorV pressure in theconduit238, as it changes Vwith-acceleratorv opening and vehicle speeds, causes a change in the line pressure regulating action of the main oil pressure regulator valve'17 as compared with its operation when theracceleratorV is in its-closed, throttle position and the vehicle is stationary. The pressure in the conduit 238 is impressed on the lower end of the main oil pressure regulator valve piston V148 through the port 158 and tends to move the piston` 148 upwardly against its spring 153 to more fully open the port 154 orthe ports 155 and 159 depending on which of these ports is,regulating,.with the driven'shaft pump 101 being inactive in one case and active in the 'other case. The piston 148 thusvents the line'pressure conduit 141 less and maintains the line pressure in the conduit 141 at a higher value-as the compensator pressure in the conduit 238 decreases and acts conversely to maintain line pressure at a lower value as the compensator pressure increases. yAs vhas been explained, the compensator pressure in the conduit 233 increases with increasing governor. pressure in the conduit y241 and increasing vehicle speed and decreases with increasing throttle pressure and throttle opening. Therefore,V the line pressure, which is ini-V tially applied to the servo motor 117 for the front brake 34 andralso throughthe piston 59 for the front clutch 32 forV engaging these friction devices when selector valve piston 242 is in its D2V position, increases with accelerator opening and decreases with increasing vehicle speed. The line pressureV is made to increase with increasedV accelerator` opening so that the lfront clutch 32 and front brake 34 having the capacity to take the additional torque from the vehicle engine which results from Vdepression of the accelerator 192 and'opening of the engine throttle. As has Vbeen hereinbefore explained, the'hydraulic torque converter 31 is of theusuallype providing a decreased torque multiplication as'th'e speedV increases; and, therefore, line pressure can be and is decreasedwith increasing governor; pressure and vehicle speed, since the engaging devices and the gearing behind the torque converter 31 need take a decreasing torque with a decreasing torque multiplication of the torque converter 31. The line pressure is also supplied to the servo motor for the brake 35 and to the piston 65 for the clutch 33 for engaging theseV friction devices when the transmission is in low speed drive, at times, or high speed drive, as will be described. T he line pressure is made to vary as above described, inaccordance with throttle opening and vehicle speed, so that the engaging pressures of the friction brakes and clutches are just a little higher than is required to carry the torque by each of these clutches and brakes as the vehicle speed and engine' throttleopening vary. It has been found that, if these clutches and brakes are engaged for changing drives through the transmission with such engaging pressures, which are just a little higher than suicient for carrying thetorque, the engagement of the friction engaging devices and the consequent completions of the power trains are relatively smooth.

The compensator pressure inthe conduit 238 functions onV the low oil pressure regulator valve 108 to cause an increase in the pressure within the torque converter 31 as the accelerator is depressed and to cause a decreaase in the pressure within the torque converter 31 as the vehicle speed increases. The compensator pressure is appliedto the lower end of the regulator valveV 168 and tends to move the piston 1651i upwardly against the action of the spring 164 so as to increase the metering effect'between the land 162 and the lower edge of the port 163, thereby relieving a greater amount of Huid from the torque converter 31 owing through the outlet conduit-172 of the torque converter 31. Thus, as the compensator pressure in the conduit 238 increases, the bleeding eicct of the valve 168 is increased to decrease the egaal-toer.

fluidrpressure in tHe-.converter 31; and, as th'e'compensztor pressure: decreases; .this bleedingetectt decreases'. tof cause an increase in the pressure. in the'torque converter."

31. Thos, the pressure in the torque converter 31 is increasedasfthe `vehiclesaccelerator 4 is moved toward open.y throttle position, andthe pressureiin the .torque converter." This regulat4 ing action of the.liuid'pressure'in.theftorque converter 31. is provided, since a greater tiuid pressure is required in' is decreased asthe-vehicle speed. increases;

the torque converterwith increasing `torque output-'of the vehicle engine,v and a=decreasing pressure torque converter 31 is sufiicient with decreased torque Amultiplication by theV torque. converter withincreasing vehiclel speeds.

The 2-3 shift .valve 111 hasthegovernor-pressnre from the conduit `2i1,impressedi on it through the `cranch conduit 239 and the ports271. and 269; The governor pressure is eifectiveon theiupper end of the valve piston 260` and on the upperi'surface. or" theland .2611 andtends to move the piston260fandthe piston 259 downwardly out of the intermediatespeed positions of the pistons in which they are illustratedlinto their high speed drive positions.

This movement ofthe valvepistons 260 and 259 is The plugZSS functions as Ya regulator valve topro vide the shift valveeplugpressurel effective on the.land 261. to the lower end of the. Vplug258 tends to move the plug against the action offthe spring-'26610 as to'open the port 267 and therebyv supply pressure totheconduit 303y and the portiZS'of the 2-3 shift valve. The pressure supplied to the port 26Sows into the cavity for thel valve piston 259 and'acts onv the upper end of the plug 258 tending to return the plug 25S-downwardly to a position blocking the port'267. The plug 258 thus functions as aregulating valve,opening the port 267on-anincrease in throttleV pressure and closing the port 267"wh`en the pressure within the conduit 303 Tand within the cavity for thepiston 259,` which is termed the shift valve plug pressure, becomes suicienti to' augment the force. due to the `spring 266 suiiiciently 'so as tomove the plug 258 downwardly. This shift valve plug pressure increases with throttle pressure but is less than throttle pressure by a predetermined amount due'to the force provided by the spring 266 on the plug 258. This -shift valve plug pressure intheccavityfor the Apiston 259 is applied on thev lower face of `the land' 261 and also, in addition'to the othertwolforces above mentioned, tends to hold the piston 259v from movement downwardly into its high speed drive position.

When the governor" pressure in the conduit 241, which is appliedto the 2-3 shift valve 111 through the ports.

271 and 269, becomes'suthciently great, so that it overcomes the force on the. pistons 260 and 259 due to the shift valve plugpressuref' on the lower' face ofthe land 261, the force due to the spring 265, and theforce due to thethrottleu pressure on the plug 258' exerted through thefspring 266y on the piston 259; the pistons 258,

259 and 260 moveto the limit of their movement downwardly into their Vhigh speedpositions in'which the groove betweenV the lands 264fand263 connects the ports 274 and 273. Line pressure issupplied to the port 274 of the 2-3 shift valve-111 from the conduit 282 and the port 246 in the manual .valve-102, and line pressurethus ows between the. lands 263 and264, the port 273 andvthe The throttle pressure in theY conduit 215' applied'- 18 conduit=281- to the piston165for the rea'r clutcli`33` andl engages th'erearciutch'33Lv The front clutch 32`rernains engaged, and the high speed power train is thus completedthrough the transmission.

The line pressure in the conduit 281 provided by the valve 11d when the piston 259 is moved into its high speed position is lalso supplied to the disapply cavity 123 of the servo motor 117 for the front brake 34. The piston 259 in its high speed drive position connects the ports 277 and276 by means of the groove between the lands 262 and 263, and line pressure ows from the conduit 281, through the ports 277 and'276, the conduit 345, the-port 32S of the orifice control valve 109, the groove between the lands 331Y and 332V of the orifice control valve piston 330, the port 340 and the conduitV 336 to the disapply cavity 1230i the servo motor 117 for the front brake 34. The orifice control valve 109 is under the control of throttle pressure in the throttle pressure conduit 215 which is applied on the upper end o-f the orifice control valve piston 330 through the port 337. The throttle pressure holds the piston 330 movedto the limit of its movement downwardly as seen in the gure against the action ofthe spring 335 lwhenever the accelerator is depressed to a substantial extent to provide a substantial throttle pressure. It is assumed that this change from intermediate speed'drive to high speed drive` is made when the accelerator is at some open throttle position so that the uppery port 338 and the port 340 arel completely opened withV respect to each other; and, therefore,l the uid flowing thro-ugh the conduit 345 to the disapply cavity'123 of the servo motor 117 is not impededV by the restriction 346 of the orice control valve 109.

The'line pressure supplied to the disapply cavity 1230iV the'servo motor 117 augments the action of the spring 124 to move the piston 118 of the servo motor 117 back into its brake disapplying position, such movement being against the action of the linev pressure within the cavity 122foffthe servo motor 117. The'disengagement ofthe brake 34` breaks the intermediate speed drive.

A downshift from high speed driveto intermediate, speed' drive' may be obtained with the accelerator 192 released'and'with the vehiclecoasting with decreasing speed `to a stop. Under these conditions, the governor pressure supplied to the ports 271 and 269=of the 2-3 shift valve 111 is decreasing, andthe throttle pressure appliedtothe plug 258 and the shift valve plug pressure. applied on the lower face of the land' 261 are substantially zero. Eventually, the governor pressure will decrease to the point at which the springs 266 and 265 are effective so as to move the pistons 259 and 260 upwardly to the limit of their movement into the inter"- medi'atespeed'positions of the pistons. r1`he line pres' sure atthe port 274 in the intermediate speed position of the piston 259 is blocked by the land 263, and the conduit 281, which has fluid pressure applied to it for completing the high speed drive, is drained to the sump through the port 273, the groove between the lands 263 and 264, the port 272, the conduit 350, the conduit 363, the port 357, the groove between the lands 352 and 353 of the reverse inhibitor valve 115, the port 358, the conduit 364 and the port 252 of the manual valve 102:

The clntch.33 connected with the conduit 281 is thusA released.

The disapply cavity 123 of the servo motor 117 forthe-v front brake 314 is drained for this change of drive through the orice control valve which functions under these conditions to retardY the drain from the cavity 123-so'asV` to cushion the engagement of the brake 34 and prevent an unduly harsh completion of the intermediate speed drive. Since the accelerator is released, the throttle pressure in the conduit 215 is at substantially zero value, and the spring 335" of the orifice control valve 109ris eHectiveto hold the valve piston 330 at the limit of its movement upwardly so'as to block the ports 339 and 340 with respect to the port 338.A Pressure drains front- 109, the port 342, the conduit 348, the port 29S, the' groove between the lands 287 and 288 and the b-leed port 296. In D2 position of the manual valve 102, as has been previously described, the 1 2 shift valve piston 284 is held at the limit of its movement downwardly against the ac-tion of the spring 304 by line pressure impressed on its upper end, and the groove between the lands 287 and 288, under these conditions,l thus connectsl the ports 295 and 296. Since the fluid from the releaseV cavity 123 of the servo motor 117 drains -through the restriction 346, application of the brake 34 is delayed, thereby smoothing the shift from third speed ratio to second speed ratio with the accelerator in closed throttle position. Y

A kickdown, that is, a downshift at open throttle position of the accelerator 192, may be had due to the action of the downshift valve 103. Movement of the accelerator 192 to an open throttle position and a corresponding' movement of the downshift valve piston 186 connects the ports 190 andl 189 by means of the groove between the landsV 187 and 188, The port 198 is connected with the lineY pressure supply conduit 141, and line pressure is thus supplied through the port 189 and the conduit 283 connected therewith to a port 278 of the 2-3 shift valve 111. Assuming that the transmission is in direct drive, and the pistons 258, 259 and 260 are in their direct drive positions to the limit of their movement downwardly, the port 2,78 is Yopen with respect to the land 261; and line pressure from the port 278 is thus applied onto the lowerface of the land 261. This application of line pressure movesY the pistons 260 and 259 to the limit of their movement upwardly into their intermediate speed drive positions, assuming that the vehicle is not traveling at an unduly high speed at which the governor pressure applied to the pistons 260 and 259 through the ports 269 and 271 would be suiiicient to prevent this movement. This shift valve piston 259 in its intermediate speed position drains the conduit 281 as previously described so as to disengage the rear clutch 33.

The 2-3 shift valve 111 in its intermediate speed drive position also connects the ports 275 and 276 by means of the groove between the lands 262 and 263 as has been previously described, and the disapp'y cavity 123 of the front brake servo motor 117 is drained through the orifice control valve 109, the 2-3 shift valve 111 and-the l-2 shift valve 113 as previously described. For a kickdown condition, when the accelerator is in its open throttle position, the throttle pressure in the conduit 215 is relativelyhigh,Y and this is impressed through the port 33.7 on the land 331 of the orifice control valve 109 holding the piston 330 of this valve at the limit of its movement downwardly lagainst the action of the spring 335. In this case, therefore, draining of the conduit 326 and the release cavity 123 of the servo motor 117 takes place around the restriction 346, through the port 340, the groove between the lands 331 and 332 and the port 338, so that the application Vof the front brake 34 is relatively rapid as is desired under high engine torque conditions.

The manual valve 102, in its Dl position, so controls the transmission that it will start in low Yspeed `drive and Von increasing vehicle speed will shift into intermediate speed drive and thereafter will subsequently shift into,

high speed drive. The manual control valve piston 242 in its D1 position connects the same ports with the line pressure supply port 249 as were connected in the D2 position of the manual Valve piston 242, with the exception that the port 253 is blocked with respect to the port 249 and is drained through the front end of the cavity in which the manual valve piston 242 is disposed. The

'20 release of uid pressure in the port 253 causes a corresponding bleeding of uid pressure from the lower end of the range control valve 114, the flow being through the port 310, the conduit 312,and the portl 253. The

. upper end of the range control valve 114 is connected by means of the port 307f`with the goverhorpressure output conduit 241, and the governor pressure is exerted on the I upper end of the range control valve piston 305 moving it to Ythe limit of its movement downwardly, whenever there is any governor pressure with movement of the vehicle, so that the ports 307 and 308 are connected. The' governor pressure is thus supplied through the conduit 311 and the port 291 on the upper end of the 1-2 shift valve 113. Prior to such movement, assuming that the valve 102 is put into D1 position when the vehicle is stationary and the governor pressure is zero, the conduit 311, together with the upper end of the cavity in which the piston 284 is disposed, are drained through the ports 309 and 310 connected whenever line pressure is applied on the lower end of the range control valve piston 305 as in the D2 range. The spring 304, under these conditions, holds; the 1-2 shift valve piston 284 upwardly in its low speed position and thus assures that the piston 284 is in its low speed position when'a start is made in the Dl range.

The 1,-2 shift valve piston 284, when inY its low speed position shifted to the limit of its movement upwardly, connects the ports 294 and 295 byvmeans of the groove between the lands 287 and 288. The port 294 carries line pressure from the conduit -254'and port 248 of the manual valve 102, and line pressureis thus supplied to the conduit 348 connected with the port 295. Fluid pressure flows from the Yconduit 348 and through the ports 342 and 341 and between Vthe lands 333 and 334 of the orifice control valve 109.A The iluid pressure flows through the conduits 347 and 386 and the restriction 385 to the port 381 of the check valve 100, thence through the port 380,V and conduit 384 to the port 324 of the transition valve however, the pressure is blocked in the transition valve 110 by the land 317. Fluid pressure also ows from the conduit 347 through the port 275, the groove between the lands 262 and 263 of the valve 111, the port 276, the conduit 345, the ports 339 and 340 andthe conduit 326 to the port 319 of the transition valve 110 to raise the pistons 313 and 314. The ports324 and 323 are thus connected so that fluid pres- Sure ows through the conduit 327 to the servo 125 for engaging the rear brake 35. f

Line pressure also flows from the conduit 343 to the disapply cavity 123 of the servo motor 117, maintaining the brake 34Vdisengaged as has been previously described in connection with other conditions of operation kof the transmission.

In the D1 position of the manual valve k102, the port -247 and its connected conduit 366 remain supplied with line pressure as in the D2 position of the manual valve piston 242, and this linepressure is supplied through the reverse inhibitor `valve and the conduit 365 to both the front clutch 32 for holding the clutch 32 engaged and also to the governor valve 1'16.` vSince the control valve114, the conduit 311V and the port 291 onthe upperrend of the 1-2 shift valve 113, tends to move the 1 2 shift'valve piston 284 from its rlow speed position, in which it is illustrated, to its intermediate speed position whichis atthe limit of its movement downwardly. The piston 284 moves from its low to its intermediate speed position against the action of the spring 304,

and the shift valve plug pressure also opposes 'this vmovementof thel-Z shift valve piston 284.' `As has been assigner;

previously expiained,. the shift valve plug. pressure is. present inthe ports 267 and 26S of the 2-3 shift valvev 111, and the shift valve plug pressure is transmitted through the conduit 303, the port 298, the `groove between the lands 285 and 2S5of the piston 234fwhen it is in itslowspeed position, andthe ports299 and `301 tothe*l lower end of the piston 284. When thevgovernor pressure increases sufficiently to overcome the shift valvel plug. pressure and the orcedue to-thespring 304, the` 1-2 shift valve piston 284 moves to the Vlimit of its movement downwardly into its intermediatespeed position.

In the intermediate speedvposition ofthe valve 113,J

the. port 294 carrying linepressure is blocked; and! the port- 295, which in the low speed position of the 1-2:

shift valve piston 284 hasline pressureA appliedv toit, is drained to thefsurnp through the -bleed port 296 and the groovebetween the lands 237 and 288. The disapply cavity 123 of the front brake 34 is drained through theV conduit 325, the port 341),' theport 338. connected with the portv 346 by means of. the groove between the lands 331 and 332 of theV orice control valve 109, the conduit 345, the port 276,.the groove between the lands 263` and 262, the port 275, the conduit3fi7, the ports- 341 and 342, the conduit 348, the port 295, the groove between the lands 28S and 237 and the bleed port 296. It is assumed at this time that the oriiice control valve piston 33 is moved to the limit of its movement downwardly as seen in the iigure against the action of the spring 335 by throttle pressure existing in the conduit 215 and applied to the land 331 of the orifice control valve. The brake 34 is thus applied, and since the clutch 32. remains applied, the transmission is now in intermediate speed drive.

A subsequent upshift to` high speed drive is obtained through .the action ofthe 2-3 shift valve 111. This valve issubject to the governor pressure that increases with the speed or the vehicle, and this valve 111 is moved into its-high speed position to complete the high speed drive by action of the increasing governor pressure in the same manner as in the D2 range.

A shift from direct drive to intermediate speed drive with the accelerator released and the vehicle speed decreasing or when the accelerator is moved to an open throttle lticlidown position :nay be had in the Dl range inthe same manner as in the D2 range.

A1 downshift from intermediate speed ratio to low speed-ratio also may be obtained while the vehicle is traveling in intermediate speed by moving the accelerator 192- to its irickdown position, and such change in drive wili occur assuming that the speed of the vehicle is not undulyhigh. As previously described, when the accelerator 192 is in its kickdownposition, the downshift valve piston 186 connects the ports 1313 and 189 thus supplying line pressure to the Yconduit 283. The line pressure iiows froml the conduit 233 to the port 297 of the 1-2 shift valve 113, and line pressure is effective on the large diameter land 287 tending to move the valve piston 284V upwardly into its low speed position against thev governor pressure effective on the upper end of the piston 284. Assuming that the vehicle speed and the governor pressure are not unduly high, the piston 23d will move upwardly into its low speed position. Line pressure iiows from the conduit 254 through the port 294 and the groove between ther lands 237 23S of the l-Z shift valve 113 and into the port 295 and the conduit 34S for completing the low speed drive as has been previously described.

TheV 1 2 shift valve piston 284 may also be allowed tomove from its intermediate speed position to its low speed position simply by allowing the vehicle to gradually decrease in speed with a resultant decrease in gover-norV pressure so that the spring 394i is effective to movetheY piston` 234 back to its low speed position. Underthese conditions, the 1-2 shift vaive piston 284 williiagain provide line pressureto the conduit 348 for 22' releasing the front-hrakefe-to again-'cause' completion; of the low-speed power. train. Therear servo check' valve functions onvsuch aV downshift to eiiectivelyvinsert the restriction-385-into the' supplyl line-384- connected tof the servo motor 125"forthe'rearibrakev35-whenever the throttle pressure 4is belowascertain'V Value,.since the' spring 379rholds the piston -'leinlitsiillustrated position Vunder these conditions, and the' engagementnof the rear' brakeY 35 is thus cushioned to preventan. unduly,harsh.iengage ment; When the acceleratoris:depressed,the:restriction 385 isby-passed by thevalve 100, Ythe piston.376 being moved upwardly againstthe-spring V376 soxasztoconnect. the restriction by-pass p,ortsf382fand 380;

The transition valve functions to .prevent .thesup-w ply of'pressure. through theeconduit327'to theservo 125 until there has been` a predetermined degree of disengagement of the brake 34, asfdetermined by the-pressure4V within the disapply cavity 123of they frontbrake servo 117. The pressure in ther-conduit 326 supplied to the disapply cavity 123 ofthe servo 117 is also applied on the piston 313 of the valve 110`through the port 319, and the land 317 effectively blocks the port 324 with respect to the port 323 until the pressure within the cavity 123 is suiiicient to raise the'transition valve piston 314 against the action iof the; spring 318. Until such move# ment of the piston 314, `application of pressure throughY the conduit 327 to the servo 125 for the rear;brake 35 is prevented so thata predetermined disengagementof the brake 34 must occurbefore initiation offengagement Acf the brake 35 occurs.V

When the manual valvepiston 242 is moved intoitsV L position, assuming that-this is'done while the Vehicle; is at rest, the lowvspeed'power train through the trans` mission will be completed. .The'manual valve piston .242m its L position connectsthe ports 24S and 247 with the iinefpressuresupply port 249V by means .of lthe groove between the lands 244and 2413 and connects the port 251 with the iine'pressnre supply port 251), the latter being connected along with the port 249 with the line pressure supply conduit 141. The line pressure supplied to the port 247 and the conduit 366 connected therewith supplies pressure as in previous drives through the reverse inhibitor valve to the front clutch 32 for engaging it and also to the governor valve 116. As in previous drives, the line pressure supplied to the port 24S and the conduit 254 provides line-pressure to the apply cavity 122 of the servo motor 117 for the front brake 34 and also to the port 294 of the 12 shift vaive 113. Line pressure is supplied fromV the port 250 of the manual valve 12 between the `lands 244 and 245 to the port 251 and thereby to the conduits 255 and 302. The line pressure in the conduit 255 ows through the port 191, the groove between the lands 187 and 138 of the downshift valve 163, the port 189 and the jconduit 233 to both the port 278 of the 2-3 shift valve 111 and also to the port 297 of the l-2 shift valve 113. The line pressure supplied to the port 278acts on the lower face of the land 2161 and holds the 2-3 shift valve piston 259 upwardly in its intermediate speed position regardless of subsequent increases in vehicle speed and governor pressure.

The line pressure within the cavity for the 2-3 shift valve aiso flows through the port 268, the conduit 303, the port 298, the groove between'the lands 235 and 285 of the l-f. shift Valve 113 andthe port 299 to the port 361, so that the line pressure is impressed on the bottom end of the l-2 shift valve piston 284 tending to hold the piston upwardly regardless of increases'in governor out-V put pressure.

The line pressure in the conduit 332 iiows through the port 292 of the 1 2 shift valve 113 and is impressed on the lands 289 and 29d, and the line pressure so appliedA also tends to hold the shift valve 284 upwardly in its low speed drive position. The l-2 shift valve, when so held in its low speed position, supplies uid'pressure to the conduit 348 through the ports 294 and 295,'and as' has been previously explained, uid pressure is sup-1 plied from the conduit 348 eventually to the release 'c'av` ity 123 of the servo motor 117 forY the front brake 34 through the conduits'347, 345 and 326.

The line pressure in the conduit 326 also acts through the port 319 on the lower end ofthe transition valve 110 and moves the pistons 313 and 314 upwardly against the spring 318. The line pressure flows also from the con-4 duit 347 through the conduit 386, the rear servo checkl valve 100, the conduit 384, the ports 324 and 323 of the transition valve 110 and the conduit 327 to the servo y modulator valve 106. The line pressure as so applied to' the left end of the modulator Yvalve 106 moves the piston 203 of this valve to the limit of its movement to the right, so that this valve piston connects together the ports 213, 210 and 212. The throttle pressure in the conduit 215 and supplied to the port 210 is thus supplied to both the ports 212 and 213 and thereby through the conduits 240 and 239 to the ports 230 and`231 of the compensator valve 105. Line pressure is thus supplied not only to the land 222 but also to the land 223 of the compensator valve 105 tending to maintain the land 221 blocking the line pressure supply port 234. The compensator pressure in the conduit 238 thus is lower for the low range drive than for the other forward drives.

v.Line pressure is also supplied from the conduit 395 to the port 390 of the low range valve 101 to move the pisi ton 387 to the limit of its movement to the right as seen in the drawing. This has the eiect of disconnecting the left end of the compensator valve 105 from the governor pressure that exists in the conduit 241 and exhausts the left end of the compensator valve through the port 392, the groove between the lands 389 and 388 and the port 391. Governor pressure is still applied through the port 232 on the right end of the compensator valve 105, and this governor pressure augments the action of the throttle pressure in the conduits 239 and 240, tending to move the piston 217 to the left. The full throttle pressure appliedv through the conduits 239 and 240 on the compensator valve 105 and the removal of the goveror pressure from the left end of the compensator valve 165 by the low range valve 101 have the efect of materially decreasing the compensator pressure in the conduit 238 and consequently increasing line pressure in the conduit 141. Due to the removal of governor pressure on the left end of the compensator valve 105, line pressure no longer decreases to a minimum value with increases oi"V vehicle speed and governor pressure. The governor pressure remains applied to the right end of the compensator valve 105 and augments the action of the throttle pressure in the conduits 239 and 240 and causes the line pressure to increase rather than decease as the vehicle speed and governor pressure increase. As the vehicle speed diminishes, the governor pressure electiveron the right end of the compensator valve diminishes accordingly, and the normal coast or idle line pressure exists with such diminishing of governor pressure. Thisincrease of line pressure with increases in vehicle speeds, as contrasted to a decrease in line pressure with increases of vehicle speed previously described, is provided for proper non-slipping engagement of the front brake 34 when the selector 256 is moved into its L position when the vehicle is traveling in direct drive, as will now be explained. Y

Assuming that the vehicle is traveling at a substantial speed in direct drive in either its Dl or D2 range, and the selector valve 102 is then moved into its L position, the transmission will be downshifted into its intermediate speed drive and subsequently into its low speed drive as the vehicle speed decreases. .When the manual selector valve piston 242 is in itsL position, theconduits 302 and 283 are pressurized with line pressure, as has just been described, and the pressure in conduit 283 is transmittedV through the port 278 of the 2-3 shift valve so that thev line pressure augments the action of the springs 265 and 266 in Vmoving the 2-3r shift valve piston 259 upwardly' intoits intermediate speed position,- this movement taking place'assuming that the governor pressure is not too high. The piston` for the rear clutchA 33 and the disapply` cavity 123 of the servo 117 for the'front brake 34 are drained tol the, sump linV the same manner as has been previously described in yconnection with a closedrthrottle downshift from third to second in the D2 range, and the transmission is inV its intermediate speed drive.

Ihave found that, in such a ratio change from directy drive to intermediate speed drive, slippage of the front 'brake 34 tends to occur at the higher vehicle speeds and position at higher vehicle speeds and is undesirable fromalwear standpoint. Since the diiculty is speed conscious, the low range valve 101 has been provided which blocks the application of governor pressure tothe left end of' the compensator valve 105 allowing it to remain applied to the right end of the valve 105 to augment the action of the throttle pressure in conduits 239V and 240. The compensator pressure in conduit 238 under these conditions is thus lowered, and the line pressure is made higher for higher vehicle speeds, and due to therprovision of the higher line pressure, the brake 34Y holds withoutslipping under coast conditions Ywhen the selector valve 102 is'. moved into its L position at higher vehicle speeds, such as,

above 30 miles per hour. The low range valve, as will be observed, thus changes the regulation of line pres-. sure from values that decrease with increasing governor v speeds for the Dl and D2 drive-ranges to values that increase with increasing governor speeds in the L range, for the purpose of overcoming this slippage condition.

Line pressure is effective through the port 292 fromy the conduit 302 on the land 290 of the 1 2 shift'valve piston 284 when the piston 2,84 is in its intermediate speed drive position, tending to move Vthe piston upwardly against the action of governor pressure from the conduit 311 into the low speed position of the valve piston 284.V

When the governor pressure decreases suficiently, the piston 284 moves into its low speed position under the influence of the line pressure impressed on'the lower sur- Y face of the land 290 and also due to the action of the spring 304. VIn this position, the groove between the lands 287 and 258 of the piston 284 connects the port 294 having line pressure applied to it and the port 295,I

thus supplying line pressure to the conduit 348. The application of line pressure to the conduit 348 causes the rear brake 35 to be engaged and the front brake 34 to be disengaged by the application of line pressure to the servo and to the relief .cavity 123 of Yservo 117 f as has been previously described. The transmission is then in low speed drive.

In connection with the reverse inhibitor valve 115, it

241 effective on its lower end tending to move the piston 351 upwardly against the action of its spring' 355,. and u' increasing governor pressure will move the piston 351 upwardly in this`V manner so as to yblock the 'port 361.

Applicationcf linepressure to. the conduit 365 is, `howsv ever-not disturbed; since when thef piston 351aisaso.l moved, it connects the ports 359- and 360 by means of; the groove betweenthe lands 353 and 354, and the.port 359 is supplied with line pressure for all.,forward drive. positions'of the manual selectorvalve piston 242.. from. the port 248 and the conduit 254.

The manual selector valve piston 242 is.placed'in:.its.v

Rposition-in order to cause completion .offthereverse drive through the transmission. In this position, the. groove between the lands 243 and 244 of the valve piston 242 connects the line pressure supply port..249. with the port 243, and the groove between the lands 244V and 245 connects the line pressure supply port 2502with". theports 251 and 252. The line pressure supplied tothe port 243 flows through the conduit 254, as -for the otherV drives previously described, to the brake engaging ,cavity 122 of the servo motor 117 for the front brake 34 and ,'to. the port 294 of the. 1-2 shift valve 113. Line pressure` iiows from -'the port 251, as for the low range drive just described, to the throttle modulator valve 106 and'the low range valve 101 for increasing the line pressure, to

the ports 273 and 292 of the 2-3 shift valve 111 and the. 1 2 shift valve 113 for maintaining these valves in theirA downshifted positions and through the 1-2 shift valve 113N through ports 294 and 295 to the disapply cavity, 123i of the front servo 117 and to the servo 125 for the rear brake 35. The brake is thus engaged andthe brake 34 is disengaged. Line pressure ows from the port 252" of the vmanual valve 102 through the conduit 364, the.

port 35S, the groove between the lands 352 and 353 of thereverse inhibitor valve 115, the port 357 and the.

320 to the lower end of the transition valve piston 314,'

and since line pressure is also present in the .conduit 326 from tte ports 294 and 295 in the 1-2 shift valveV and' from the port 24S in the manual valve 102 as described previously yin connection with the low range drive, the. pressure applied to both the lower end of the piston 314 and also the lower end of the pistonY 313 causes. the

piston to be moved upwardly against"the action of i line pressure applied to its upper end and theaction of the spring 318 to connect the ports 324 and 323 by the groove between the lands 316 and 317 for supplying line( pressure to the servo 125 for the rear brake 35. The.

line pressure in the conduit 350 is also supplied ,tothe port 343 of the orilce control valve 109, and this valve remains in its illustrated position.

Line pressure is supplied from the conduit 375 to the port 374 of the saiety valve 112 and moves the'piston 367 of the safety valve upwardly against the action of its spring 370, so that the groove between the lands 369., and 368 connects the governor pressure conduit 241 with the bleed port 373. The safety valve 112 thus assures that there can be no governor pressure existing in the conduit 241 and connected conduits when the transmission control system is set for reverse drive.

The purpose of the reverse inhibitor valve 115 is to prevent the completion of reverse drive when the vehicle is traveling above a predetermined speed in forward direction, such as 10 mph. and the manual valve piston 242 is put into its R position. The inhibitor valve 115 has been designed so as to actually put the transmission in low range instead of reverse drive when the manual valve piston 242 is moved to its R position above the predetermined low forward vehicle speed.

The.. outpnt. governor pressure.. insthesrA conduit .2411VA is impressedon `the, lower .end of.the .reverse inhibitor valve. piston SSL so,.th`at.the piston'351ris atthe. upper, limit ofits vmovement abovethe predetermined low forward` vehicle speed, beingmoved against the actionofits springt 355,. Inits upper position, the piston .351 connectssthei por-ts..359 and 360.by means of the groove ,betweenthe. lnds..353.-and...354.and connects the conduit 363l tofthew.` bleed p,or=t,356.`by means of the port 357 and thegrooven betweenthe lands 352 and 353. The land 353. intheuppery position of the. piston'351also blocks the port. 358..connected with. the conduit 364 which is pressurized.L inthetreversedrive position of the manual piston `242.` The` reverseainhibitor valve thus in its upper position as.

. shiftedby. governor pressure inthe conduit 24.1'eiectively,A

supplies line pressure tothe .port 360 which engages the. front clutcht32 .and energizes the governor 116 andalso, drains the port 357 connected with the conduit 363.. Which,.byrtheapplication `of iluid pressure thereto, engages the.rear.clutch.33 for reverse drive.

The low-,range .valve 101 advantageously assures that; the line pressure applicable to the servo 117 for the brake- 34-increases rather than decreases with increasing vehicle` speed.. Therefore, when the selector Valve 102 is moved into itsV lowfrange position when the vehicle is traveling. atla substantialspeed, such as above 30 m.p.h., for the.l pnrpose..of..causing the transmission to downshift to provide. engine..braking. on the vehicle, the line pressurejstA increased suiciently so as to assure that there is no. slippagerofrthe brake 34 even rthough the brake is acting, in.a.selfdeenergizingy direction. Undue and excess wear.. of.the. brake.,band.67 is also avoided by. the provision... ofthe valve 101.

Iwish it tobe understood that the inventionisfnot to.

`be limited to the especilicconstructions andarrangements.

shown and-described, except onlyV insofar astheclaimsf. may beso limited, asit will be understood tothose skilled inthe art that changesmay be made without departingg from theprinciples. of the invention.

I claim.:

l.,Intransmission.mechanism the combination of as drive. element, adriven element, a friction engaging.; mechanism .for completing a drive between said elements. when engaged, a source-of fluid pressure, meansfor. connecting saidv pressure source with saidv engaging, mechanism to. engage it,y a speed responsive device, pressure regulator. meansv effectiveA on said pressure Source,.. meansinterconnecting said speed responsive device-and: saidregulatingmeans vsonas to cause said fluid pressureV to. decrease` with speedincreases-for one condition of.V drivebetweensaid elements, and means interconnectingv saidspeedresponsive device and said regulating means, soas to cause said iluid .pressure to increase with speedn increasesiorl another conditionrof drive between said-v elements;

2.,.In.transmission mechanism, the combination otra# drive element, a driven element, a iluid pressure engaged frictionengaging mechanism forv completing a drive between. said elements when engaged, a source of lluidr pressure, .means for connecting said pressure Vsource with .Y said,-.engaging mechanism-to engage it and includinga manually controlled selector providing one condition of drive in one position thereof and another condition of drive in another position thereof, a speed responsive device, pressure regulating means effective on said pressure source, means under the control of said manual selector and interconnecting said speed responsive device and said regulating means so as to cause said fluid pressure to decrease with speed increases for one of said conditions of drive between said elements, and means under the control of said manual selector and interconnecting Said speed responsive device and said regulating means So as to cause said fluid pressure to increase with speed increases for the other of said conditions of drive between said elements.

openssl" 27 3.`In transmission mechanism, the combination of a drive element, a driven element, a fluid pressure engaged friction engaging mechanism for completing a drive between said elements when engaged, a source of uid pressure, a manually controlled selector valve having two diierent Ydrive positions in both of which it may cause connection of said pressure source with said engaging mechanism to engage it, a governor responsive to theY speed of said driven element, arpressure regulating valve eiective on said pressure source, means interconnecting said selector valve and said governor and said regulating valve so as to cause said uid pressure to decrease with speed increases of said driven element in one position of said selector valve, andtmeans interconnecting said selector valve and said governor and said regulating valve so as to cause Said fluid pressure to increase with driven element speedv increases for the other position of said selector valve. e Y 'Y 4. In transmission mechanism, the combination of a drive element, a driven element, means for providing a power train between said elements and including planetary gearing and a friction brake for a reaction member of said gearing, said friction brake being self-energizable for a drive from said drive element to said driven ele' ment land being self-deenergizable for a drive in the opposite direction, a source of uid pressure, means for connecting said pressure source with said friction brake to engage it, a speed responsive device, pressure regulator means etective on said pressure source, means interconnecting said speed responsive device and said regulator:

means so as to cause said fluid pressure to decrease with speed increases for a drive from said drive element to said driven element, and means interconnecting said speed responsive device and said regulator means so as to cause said uid pressure to increase with speed increases for a d'rive between said elements in the opposite direction.

5. In transmission mechanism Vfor an automotive vehicle with a driving engine, the combination of a drive element, a driven element, means for completing a plurality of drives between said elements and including planetary gearing and a fluid pressure engaged friction brake for a reaction member of said gearing for completing one of the drives, a source of iiuid pressure, means for connecting said pressure source with said friction'brake to engage it and including a manually controlled selector valve having a vehicle driving position and an lengine brakingposition, a governor responsive to the speed of said driven element, pressure regulating means eiective on said pressure source, meansginterconnecting said governor and said regulating means and said valve so as to cause said uid pressure to decrease with driven element speed increases for the vehicle driving position of said selector valve, and means interconnecting said governor and said regulating -means and said valve so as to cause said uid pressure to increase with speed increases of said driven element for the engine braking position of said selector valve.

Y6. In transmission mechanism for an automotive vehicle with'a driving engine, the combination of a drive element, a-driven element, means for providing a plurality of different ratio drives between said elements and including planetary gearing and a fluid pressure engaged friction brake for a reaction member of said gearing for completing a certain speed drive, a source of uid pressure, a governor responsive to the speed of said driven element, means for effectively connecting said pressure source with said brake and said drive providing means and including a selector valve havingV arvehicle driving position and an engine braking position, said governor being eiective for changing the transmission mechanism from a lower ratio drive completed by said friction brake to a higher ratio drive in the vehicle driving position of the selector valve and being effective for changing the transmission mecha.

drive Vin the opposite direction, a pressure regulating valveeffective on said pressure source, hydraulic means interconnecting said governor and said regulating valve and Ysaid selector valve so as to cause said uid pressure to decrease with driven element speed increases when said selector valve is in its vehicle driving position, and hydraulic means interconnecting said governor and said regulating valve and said selector valve so as to cause said uid pressure to increase with driven element speed increases when said selector valve is in its said other position. Y

Y 7. In transmission mechanism for an automotive ve hicle having a driving engine, the combination of a drive element, a driven element, means Vfor providing a drive between said elements and including planetary,YY gearing and a fluid pressure engaged friction brake for, a reaction member thereof completing the drive when engaged, said frictionbrake being self-energizable for a drive from said drive element to said drivenelement and being self-deenergizable for a drive in the opposite direction, a source of uid pressure, means forl connecting said pressure source with said friction brake to engage it and including aselector valve having a vehicle braking position and an engine driving position and eiiective in both to make said connection, a pressure regulator valve elfectiverfor regula'ting the vpressure of said source, a governor driven by said driven element and providing a governor ud pressure that increases with the speed of said driven element, said regulator valve'having two diierent opposing lands thereofuconnected to said governor pressure so that the pressure of said source decreases with increases in speed of s'aid driven element for the vehicle driving position of said selector valve, and a shuttle valve under the control v References Cited in the le of this patent UNITED STATES PATENTS 2,766,639 Rosenberger Oct. 16, 1956 

